N-acylated piperazines



Patented Feb. 13, 1951 PATENT OFFICE N-ACYLATED PIPERAZIN ES -Arthur L. J acoby, Western Springs, 111., assignor to National Aluminate Corporation, Chicago, 111., a corporation of Delaware No Drawing. Application June 11, 1947, Serial No. 754,061

This invention relates to high molecular weight acylated piperazines, and more specifically to new chemical compounds of that character having the general formula:

where X is the alkyl radical of an aliphatic carboxylic acid which may contain one or more double bonds and may contain substituent groups, e. g., hydroxyl, that is XC=O is the acyl radical of such an acid; and Z is the acyl radical of an aliphatic carboxylic acid, an aromatic carboxylic acid, or an .arylsulfonic acid.

The present application is a continuation-inpart of my copending application Serial No. 436,494, filed March 27, 1942, now Patent No. 2,428,801.

The compounds of this invention, when conforming to certain structural limitations as more fully set forth hereinafter, are greases or waxes of varying degrees of hardness and are valuable as substitutes for natural waxes, as constituents of coating compositions, as corrosion inhibitors, as defoamers, and as intermediates for the preparation of other valuable compounds.

For the sake of convenience, the compounds of this invention may be divided into three classificaltions.

First, there is the class consisting of diacyl piperazines, in which both acyl groups are de,

rived from aliphatic carboxylic acids and in which the two acyl groups are substantially equal in the number of carbon atoms in each, and in which each acyl group is derived from an acid containing at least 8 carbon atoms (X in the general formula would contain at least '7 carbon atoms). Examples of such compounds are dioctanoylpiperazine, didodecanoylpiperazine (dilaurylpiperazine), and dioctadecanoylpiperazine (distearylpiperazine) Second, there is the class consisting of diacyl piperazines, in which both acyl groups are derived from aliphatic carboxylic acids, but where the two groups. differ widely from each other with respect to the number of carbon atoms in each. In this class, the large acyl group should be derived from an acid having at least 12 carbon atoms (X in the general formula would contain at least 11 carbon atoms). An example of a compound falling into this class is N-acetyl-N'-laurylpiperazine.

The. third class consists of diacyl piperazines in which one .acyl radical is derived from an all,-

Claims. (Cl. 260-268) 2 1 phatic acid of at least 12 carbon atoms (X in th general formula would contain at least 11 carbon atoms), and the other acyl radical is that of an aromatic carboxylic or an arylsulfonic acid. Examples of such compounds include N-lauryl-N'- benzoylpiperazine and N-stearyl-N'-benzenesulionylpiperazine. i

The compounds of this invention may be prepared in numerous ways, and under a variety of conditions. Thus, from the standpoint of starting materials, it is possible to effect the acylation of 'piperazine by a number of acylating' agents including the acids, acid halides, acid amides, and esters. drate, may be employed as a starting material. The conditions under-which the preparations are carried out may also vary widely, it being possible to work below, at,- or above atmospheric pressure, with or without a solvent, or at various temperatures, as will be understood by one skilled in the art.

It is not intended that the invention be limited in scope to acylated piperazines prepared by any particular route, or in any particular manner, and the following examples are given merely by way of illustration.

Example I A mixture of 5.8 grams (0.03 mole) of piperazine hexahydrate and 15.4 grams (0.06 mole) of palmitic acid was heated carefully until most of the water had been expelled and frothing ceased.

Then it was stirred at 160 C. for about 3 hours. When cool, the product was a tan wax.

After recrystallization from methanol or acetone,

' Example. II

Commercial stearic acid. having a mean molecular weight of about 269. Was employed in this preparation. Sixteen grams (0.06 mole) of the acid and 5.8 grams (0.03 mole) of piperazine hexahydrate were mixed and heated carefully to expel the most of the water. Then the product was stirred 2.5 hours at 150-160 C. Whencool, the product was a brown Wax.

Substantially the same product was prepared, but in a purer form, by the reaction of 2.58 grams (0.03 mole) of piperazine and 17.1 grams (0.06 mole) of purified stearic acid. This product was also. a wax, and after several recrystallizations from methanol it melted at 83-83,? C. and

Also, either piperazine itself, or its hywas identified as dioctadecanoylpiperazine (d1- stearylpiperazine) by analysis. Calculated for C40H'IBO2N2Z N=4.53%. Found: N=4.42% and 4.43%.

The unrecrystallized product was readily soluble in benzene or carbon tetrachloride and slightly soluble in ethanol or petroleum ether.

Example III Emsmp o 1V .,8.1 grams (0.03 mole) of the commercial stearic a of Exa le .11. 5.8 grains 2- mo e o n ee a i e o eh dra o. and s s ems i-03 mole) of benzoyl chloride were condensed by the sam procedure as t i d in E amp e 111. When c l. the Product which con ain d a s bstantial proportion of NestearyleN'ebenzoylpie eerazine. was a d rn bro n was an exhib ted sho the som so bi ity he ao eris io a e product oi xample I I- Eromn V Example VI A mi ture o 22-6 eras ('93 mole.) o olo o acid. an 2.1 rams li mole o iner sins was s irred or 3 h rs a .5916 h n cool. the diol y psi e was a e r. viso us il. easily so u le i enzene. carb n, tetrac loride. han r petro eum ether.

Example VI A m ure oi 12-1 rains (ii-.03 mo oi prylic (octanoic) acid and 8.1 grams (0.042 mole). of piperazine hexahydrate was heated carefully at about 120 C. until the tendency to froth had dis d d en s r e as h u s at 1.5 160 C. When cool, the product was a brown wax which was identified as dioctanoylpiperazine by analysis after recrystallization from methanol to a melting point of 167 C. Calculated for o rmo r -7.73%. Found: ri -79% and 1 3. 3%-

name s V111 A migture of 13.7 grams (0.06 mole) of myristic acid and 5.8 grams (0.03 mole) of piperazine hexahydrate was stirred at 150-.160 C. for 3 hours' When cool, the product was. a wax which was readily soluble in benzene or carbon tetrachloride and slightly soluble in ethanol or petro:

4 leum ether. After several recrystallizations from methanol, it melted at C. and was identified as dimyristylpiperazine by analysis. Calculated for C32Hs2O2N2: lN=5.53%. Found: N=5.55% and 5.53%.

Example IX A mixture of 20 grains (0.1 mole) of lauric acid and 9.7 grams (0.05 mole) of piperazine hexahydrate was heated cautiously at about C. until the tendency to froth was gone and then stirred 2.5 hours at ISO-160 C. The product was a brown wax which, after several recrystallizations from methanol, melted at 133-134 C. and was identified as didodecanoylpiperazine (dilaurylpiperazine) by analysis. Calculated for QzgHsgQ izNz: N 6.24%. Found: N=6.35% and 6.19%.

Example X A mixture of 59.6 grams (0.2 mole) of ricinoleic I acid and 19.4: ram QQ-l mo e) oi ninerss hexahydrate was lly t about -130 01111 3 T9 i .M. e for 3 hours at -160" C. When cool, the diricinoleylpiperazine was a viscous oil, easily soluble in benzene, carbon tetrachloride, or ethanol, and insoluble in low-boiling petroleum ether.

Emmple X! A m xture oi 6.9 rams 0-03 m le) i m r s io an and 5-8 g ams (0.0 in is of nipsi zins hex h drste was heated oe hil y about ll0=120 until hot e an then stirred 2 hours at 0=i60 To the sti red was then added ,36 rams (0 .3 mole) o aoe yl chl ride a d the min iire ed is on er ool. he li aoety ii rristyi piperazine was a tan wax which was readily sold: hi in benz ne or carbon tetrachloride and sligh lr so ub e ethanol o petroleum e h rfiererel r or sts lihet on sews m lting po nt oi 744 c.

Hav ng thus descr ed inv tion, wha I o a in as now and des re to secure by Letters latent o he United statesisz 1. A iacy ted. nipsrazine which both scyl gr up are derived. iroin aliph i rboxy acids and i wh ch said a y! groups are o ostantially equal in number of carbon atoms and ach on ains at lea t 7 c bo a ms.

2- A iaoyla d. p eroz ne in hi bo h a y gr ups ar d ri ed r al phat r ox lic ao os and hi sa d s groups differ wide iroin ea h oth with resp ctv o the n mber of ca on toms n a h, he a e yl gr p c ning s ss 11 ca n a msgrou is derived from an aliphatic carboxylic acid'gr at least 12 carbon atoms and the other acyl group is derived from an arylsulf onic acid.

4. N,N-dioctadecanoylpiperazinc. I

5. N-acetyl-N'-octadecanoylpiperazine.

6, N-stearyl-N -toluenesulfonylpiperazine.

7. A diacy-lated piperazine in which one acyl group is derived from an aliphatic carbox-ylic acid of at least 12 carbon atoms and the other acyl group is derived from an aromatic carboxylic acid.

8. A diacylated piperazine from the group con: sisting of (a) diacylated piperazines in which both acyl groups are derived from aliphatic carboxylic acids and in which said acyl groups are substantially equal in number of carbon atoms and each contains at least 7 carbon atoms; (b).

3. A d e ylete pip zine i whio on x diacylated piperazines in which both acyl groups are derived from aliphatic carboxylic acids and in which said acyl groups difier widely from each other with respect to the number of carbon atoms in each, the larger acyl group containing at least 11 carbon atoms; (0) diacyiated piperazines in which one acyl group is derived from an aliphatic carboxylic acid of at 1eastf12 carbon atoms and the other acyl group is derived from an arylsulfonic acid; and (d) diacylated piperazines in which one acyl group is derived from an aliphatic carboxylic acid of at 16381112 carbon atoms and the other acyl group is derived from an aromatic carboxylic acid.

9. N-stearyl-N-benzoy1piperazine.

10. Diricinoleylpiperazine.

ARTHUR L. JACOBY.

6 REFERENCES crrEn The following references are of record in the file of this patent:

UNITED STATES PATENTS Jacobi, Berichte 66, 113-115 (1935)? 

8. A DIACYLATED PIPERAZINE FROM THE GROUP CONSISTING OF (A) DIACYLATED PIPERAZINES IN WHICH BOTH ACYL GROUPS ARE DERIVED FROM ALIPHATIC CARBOXYLIC ACIDS AND IN WHICH SAID ACYL GROUPS ARE SUBSTANTIALLY EQUAL IN NUMBER OF CARBON ATOMS; (B) EACH CONTAINS AT LEAST 7 CARBON ATOMS; (B) DIACYLATED PIPERAZINES IN WHICH BOTH ACYL GROUPS ARE DERIVED FROM ALIPHATIC CARBOXYLIC ACIDS AND IN WHICH SAID ACYL GROUPS DIFFER WIDELY FROM EACH OTHER WITH RESPECT TO THE NUMBER OF CARBON ATOMS IN EACH, THE LARGER ACYL GROUP CONTAINING AT LEAST 11, CARBON ATOMS; (A) DIACYLATED PIPERAZINES IN WHICH ONE ACYL GROUP IS DERIVED FROM AN ALIPHATIC CARBOXYLIC ACID OF AT LEAST 12 CARBON ATOMS AND THE OTHER ACYL GROUP IS DERIVED FROM AN ARYLSULFONIC ACID; AND (D) DIACYLATED PIPERAZINES IN WHICH ONE ACYL GROUP IS DERIVED FROM AN ALIPHATIC CARBOXYLIC ACID OF AT LEAST 12 CARBON ATOMS AND THE OTHER ACYL GROUP IS DERIYED FROM AN AROMATIC CARBOXYLIC ACID. 